Integrated structures and methods of forming integrated structures

ABSTRACT

Some embodiments include an integrated structure having semiconductor material within a region between two parallel surfaces. The semiconductor material has grain boundaries parallel to the parallel surfaces. At least one circuit component utilizes a region of the semiconductor material in a gated device. The semiconductor material has little if any metal therein so that the gated device has Ion/Ioff characteristics similar to if the semiconductor material had no metal therein. Some embodiments include a method in which semiconductor material is provided between a pair of parallel surfaces, and in which the parallel surfaces and semiconductor material extend between a first end and a second end. Metal is formed adjacent the first end, and gettering material is formed adjacent the second end. Thermal processing induces crystallization of the semiconductor material and drives the metal along the semiconductor material and into the gettering material. The gettering material is then removed.

RELATED PATENT DATA

This patent resulted from a divisional of U.S. patent application Ser.No. 14/942,823 which was filed Nov. 16, 2015, and which is herebyincorporated herein by reference.

TECHNICAL FIELD

Integrated structures and methods of forming integrated structures.

BACKGROUND

Memory provides data storage for electronic systems. Flash memory is onetype of memory, and has numerous uses in modern computers and devices.For instance, modern personal computers may have BIOS stored on a flashmemory chip. As another example, it is becoming increasingly common forcomputers and other devices to utilize flash memory in solid statedrives to replace conventional hard drives. As yet another example,flash memory is popular in wireless electronic devices because itenables manufacturers to support new communication protocols as theybecome standardized, and to provide the ability to remotely upgrade thedevices for enhanced features.

NAND may be a basic architecture of integrated flash memory. Aconventional NAND configuration 500 is shown in FIG. 1 incross-sectional side view and schematic view. The NAND configuration 500corresponds to pipe-shaped bit cost scalable (P-BiCS) flash memory. TheNAND string is U-shaped and extends between a source line and a bitline.The NAND memory includes control gates 512 which are spaced from achannel region 514 by gate dielectric 516.

The channel material 514 comprises semiconductor material; and may, forexample, comprise polycrystalline silicon. There may be advantages toutilizing channel materials having specific crystalline textures, butdifficulties are encountered in reproducibly forming desired crystallinetextures within the U-shaped channel material 514. It would be desirableto develop architectures having desired crystalline textures withinU-shaped NAND channel material, and to develop methods of forming sucharchitectures.

The NAND configuration 500 is one of many configurations in which itwould be useful to tailor crystalline texture within a semiconductormaterial. It would also be desirable for the new methods to beapplicable for other configurations in addition to the U-shaped NANDconfiguration 500.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a prior art pipe-shaped bit cost scalable (P-BiCS) flashmemory configuration in cross-sectional side view and schematic view.

FIGS. 2-10 show a construction in diagrammatic cross-sectional side viewat process stages of an example embodiment method of forming an exampleembodiment U-shaped NAND configuration.

FIGS. 11-18 show a construction in diagrammatic cross-sectional sideview at process stages of another example embodiment method of formingan example embodiment U-shaped NAND configuration. The process stage ofFIG. 11 may follow that of FIG. 2.

FIGS. 19-22 show a construction in diagrammatic cross-sectional sideview at process stages of an example embodiment method of forming anexample embodiment thin-film-transistor NAND configuration.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Some embodiments include methods of utilizing metal to induce a desiredtexture within semiconductor material. The semiconductor material may beconfigured to have two exposed ends, and to be between a pair ofparallel surfaces. The ends may be referred to as a first end and asecond end. The metal may be provided adjacent the first end, and thenthermal processing may be utilized to induce crystallization of thesemiconductor material utilizing the metal. The metal may travel fromthe first end to the second end during the thermal processing. A pair ofgettering regions may be provided over the second end, with a first ofthe gettering regions being adjacent the second end and a second of thegettering regions being more distal from the second end. Thermodynamicsmay drive the metal through the first gettering region and into thesecond gettering regions. Subsequently, the gettering regions may beremoved.

Specific example embodiments are described below with reference to FIGS.2-22.

Referring to FIG. 2, an example NAND configuration 10 is illustrated.The configuration comprises control gates 12, a back gate 14 and aselect gate 16; analogous to structures described above with referenceto the conventional NAND configuration of FIG. 1.

The gates 12, 14 and 16 are spaced from one another by one or moredielectric materials 18. Such dielectric material(s) may comprise, forexample, silicon dioxide, silicon nitride, etc.

The gates 12, 14 and 16 may comprise any suitable electricallyconductive composition or compositions. In some embodiments the gates12, 14 and 16 be the same composition as one another; and in otherembodiments at least one of such gates may differ in compositionrelative to at least one other of the gates.

A break is provided between a pair of the control gates 12 to indicatethat the configuration may have more than the illustrated number ofcontrol gates. The NAND configuration includes a string of memory cells(a so-called NAND string), with the number of memory cells in the stringbeing determined by the number of control gates 12. The NAND string maycomprise any suitable number of control gates. For instance, the NANDstring may have 8 control gates, 16 control gates, 32 control gates, 64control gates, 512 control gates, 1024 control gates, etc.

The NAND configuration 10 comprises semiconductor channel material 20adjacent control gates 12, back gate 14 and select gate 16. Thesemiconductor channel material may comprise any suitable composition;and in some embodiments may comprise, consist essentially of, or consistof one or both of silicon and germanium.

The semiconductor channel material is spaced from conductive material ofthe gates 12, 14 and 16 by gate dielectric 22. The gate dielectric maycomprise any suitable composition or combination of compositions; and insome embodiments may comprise, consist essentially of, or consist ofsilicon dioxide.

The channel material 20 is in a U-shaped configuration, and is part of aU-shaped NAND string. The term “U-shaped” is used to refer to structuresloosely analogous to a “U”; which may include, but is not limited to,structures which strictly resemble a “U”.

The U-shaped channel material extends between a first end 24 along oneside of the U-shape and a second end 26 along another side of theU-shape. The semiconductor channel material has a first crystallographictexture. In some embodiments, such first crystallographic texture may besubstantially non-ordered; and, for example, may be polycrystallineand/or amorphous.

The gate dielectric 22 has interior surfaces 25 and 27 on opposing sidesof channel material 20. The interior surfaces 25 and 27 may beconsidered to be parallel to one another (at least to within reasonabletolerances of fabrication and measurement), and in the shownconfiguration are U-shaped.

The back gate 14 shown to be supported over a base 28. The base maycomprise semiconductor material; and may, for example, comprise, consistessentially of, or consist of monocrystalline silicon. The base may bereferred to as a semiconductor substrate. The term “semiconductorsubstrate” means any construction comprising semiconductive material,including, but not limited to, bulk semiconductive materials such as asemiconductive wafer (either alone or in assemblies comprising othermaterials), and semiconductive material layers (either alone or inassemblies comprising other materials). The term “substrate” refers toany supporting structure, including, but not limited to, thesemiconductor substrates described above. In some applications, the basemay correspond to a semiconductor substrate containing one or morematerials associated with integrated circuit fabrication. Such materialsmay include, for example, one or more of refractory metal materials,barrier materials, diffusion materials, insulator materials, etc.

The base 28 is spaced from back gate 14 by a gap. Such gap is utilizedto indicate that there may be additional materials between base 28 andthe back gate 14.

The construction 10 has an upper surface 19 at the processing stage ofFIG. 2; with such upper surface extending across the ends 24 and 26 ofchannel material 20, and across the uppermost portion of dielectricmaterial(s) 18.

Referring to FIG. 3, gettering material 30 is formed over the second end26 of the U-shaped channel material 20, while leaving the first end 24of the U-shaped channel material exposed.

The gettering material 30 includes a first region 32 and a second region34. In the illustrated embodiment the regions 32 and 34 are two distinctlayers. In other embodiments, the regions may be comprised by a gradientas discussed in more detail below. Also, although the shown getteringmaterial comprises two distinct layers, in other embodiments thegettering material may comprise three or more layers, may comprise oneor more layers in combination with a gradient, etc. In other words, thegettering material 30 may comprise more than the illustrated two regions32 and 34 in some embodiments.

In the illustrated embodiment, the first region 32 of the getteringmaterial may comprise tungsten silicide and/or tantalum silicide, andmay be formed to a thickness within a range of from about 100 Å to about200 Å. The second region 34 may comprise silicon (for instance,amorphous silicon), and may be formed to a thickness greater than orequal to about 200 Å (for instance, a thickness within a range of fromabout 0.2 nanometers to about 10 nanometers). In operation, thecomposition of region 32 is chosen so that thermodynamics favormigration of a metal from the channel material 20 into the first region32; and the composition of region 34 is chosen so that thermodynamicsfavor migration of the metal from the first region 32 into the secondregion 34. Accordingly, metal from semiconductor material 20 may beeffectively trapped within the region 34 which is displaced from theupper surface of the semiconductor material by the intervening region32. Subsequently, the regions 32 and 34 may be removed to effectivelyremove the metal from the semiconductor material 20. The examplecompositions of regions 32 and 34 may be utilized to favor thethermodynamic drive of metal from channel material 20 into the upperregion 34. In other embodiments, other compositions of regions 32 and 34may be utilized to achieve the same thermodynamic drive. In someembodiments, both of regions 32 and 34 may be amorphous as deposited.Region 32 may have a higher amorphous-to-crystal (a-to-c) transitiontemperature as compared to channel material 20 and region 34.Accordingly, region 32 may remain amorphous while region 34 crystallizesthrough metal-induced crystallization. Such may be a basis ofthermodynamic drive of metal from channel material 20 into upper region34 of gettering material 30. If gettering material 30 comprisesadditional regions (for instance, a third region, a fourth region,etc.), such additional regions may be between regions 32 and 34 and mayhave amorphous-to-crystal transition temperatures lower than region 32and higher than region 34 to assist in transferring metal toward region34.

The gettering material 30 may be formed in the desired configurationwhich covers first end 24 while leaving second end 26 exposed with anysuitable processing. For instance, the gettering material may be formedto extend across both ends 24 and 26, and may be subsequently patternedto remove the gettering material from over the first end 24.

In some embodiments, the regions 32 and 34 may correspond to portions ofa gradient extending through material 30, rather than to specificlayers. For instance, in some embodiments gettering material 30 maycorrespond to a structure having a first stoichiometry in the firstgettering region 32 and a second stoichiometry in the second getteringregion, and having a gradient from the first gettering region to thesecond gettering region. The first stoichiometry may transition to thesecond stoichiometry along said gradient. In a specific embodiment, thefirst stoichiometry may include M_(a)Si_(x) and the second stoichiometrymay include M_(b)Si_(y), wherein the ratio of a/x is greater than theratio of b/y, and wherein M is a transition metal. In some exampleembodiments M may be tungsten and/or titanium. In some exampleembodiments the composition at the upper region of the getteringmaterial gradient may consist essentially of, or consist of silicon, andaccordingly the ratio of b/y may be zero or at least may approach zerofor the composition M_(b)Si_(y) at the upper region (i.e., b may be zeroor may approach zero at the upper region of the gradient).

A protective liner 36 is formed over gettering material 30. Theprotective liner prevents, or at least substantially impedes, migrationof metal from a subsequently-formed metal layer (discussed below withreference to FIG. 4) into the gettering material 30. The liner 36 maycomprise any suitable composition or combination of compositions; and insome embodiments may comprise, consist essentially of, or consist ofsilicon nitride. The liner may be formed to any suitable thickness, andin some embodiments may be formed to a thickness within a range of fromabout 200 Å to about 300 Å. The protective liner may be referred to asmetal-barrier material.

An opening 38 extends through the gettering material 30 and liner 36 tothe first end 24.

Referring to FIG. 4, an optional filter material 40 is formed over liner36 and within the opening 38, and metal 42 is formed over the filtermaterial and within the opening 38.

The metal 42 may comprise one or both of near-noble metal and noblemetal; with near-noble metal being metals selected from group VIII ofthe periodic table (or groups 8, 9 and 10 under new notation), and noblemetals being selected from group IB (or group 11 under new notation).Accordingly, near-noble metals include, for example, iron, cobalt,nickel, ruthenium, rhodium, palladium, etc.; and noble metals includecopper, silver and gold. In some embodiments metal 42 may comprisealuminum.

The filter material 40 may comprise, for example, titanium and/orsilicon nitride. For instance, in some embodiments the filter materialmay be a layer of titanium formed to a thickness of from about 10 Å toabout 30 Å; and in some embodiments may be a layer of silicon nitrideformed to a thickness of from about 50 Å to about 80 Å.

In some embodiments, metal 42 may comprise, consist essentially of, orconsist of nickel; and may be a layer formed to a thickness of fromabout 0.5 Å to about 15 Å.

The metal 42 within opening 38 is adjacent the first end 24 ofsemiconductor channel material 20.

Referring to FIG. 5, thermal conditions are utilized to induce metal tomigrate from material 42 into the first end 24 of the semiconductorchannel material, as is diagrammatically illustrated utilizing arrows43. The metal within semiconductor channel material 20 is utilized formetal-induced crystallization (MIC) and/or metal-induced lateralcrystallization (MILC). Specifically, the metal induces crystallographicgrain growth within the semiconductor material 20 as is diagrammaticallyillustrated utilizing dashed-lines 45. The metal-induced crystallizationtransitions a crystallographic texture within semiconductor channelmaterial 20 from the first crystallographic texture to a secondcrystallographic texture having large crystalline grains and grainboundaries parallel to the parallel surfaces 25 and 27 of the gatedielectric material 22.

Any suitable thermal conditions may be utilized to transfer metal fromthe material 42 into the semiconductor channel material. Themetal-induced crystallization of the semiconductor channel material is athermodynamically-favored process. The metal migrates into thesemiconductor channel material and then continues to move through thesemiconductor channel material until the semiconductor channel materialis entirely crystallized, provided that the thermal conditions aremaintained for a suitable duration. In some embodiments the thermalprocessing may comprise a temperature within a range of from about 370°C. to about 550° C., for at least about 10 hours.

The filtering material 40 may moderate the amount of metal reaching thefirst end 24. A small amount of metal is sufficient to induce a desiredcrystallization, and too much metal may make it difficult to fullyremove metal from the semiconductor channel material 20 in laterprocessing. Additionally, too much metal may lead to smaller crystallinegrains within the semiconductor channel material 20.

FIGS. 6 and 7 show the propagation of crystalline grains through thesemiconductor channel material 20 during the metal-inducedcrystallization, and show the grains being aligned so that grainboundaries are parallel to the parallel surfaces 25 and 27 of the gatedielectric 22 (to within reasonable tolerances of fabrication andmeasurement). The metal utilized for inducing crystallization withinchannel material 20 may stay largely along a forward edge of thecrystals propagating through channel material 20, and accordingly mayaccumulate adjacent the second end 26 of the U-shaped channel material20 at the processing stage of FIG. 7.

Referring to FIG. 8, the metal migrates from the semiconductor channelmaterial 20 into the gettering material 30 at end 26, as isdiagrammatically illustrated with arrows 43.

The metal migrates into the gettering material due to such beingthermodynamically favored under the thermal conditions utilized for themetal-induced crystallization. As discussed above, the regions 32 and 34of the gettering material are tailored so that thermodynamic forcescause the metal to be drawn into the lower region 32, and then to betransferred from the lower region 32 into the upper region 34.Accordingly, the metal eventually accumulates in the upper region 34 ofgettering material 30 as is diagrammatically illustrated in FIG. 9 bystippling within the region 34 above the second end 26 of channelmaterial 20. In some embodiments, both of regions 32 and 34 may beamorphous as deposited, and region 32 may have a higheramorphous-to-crystal transition temperature as compared to channelmaterial 20 and region 34. Region 34 may be at least partiallycrystallized through metal-induced crystallization while region 32remains amorphous, and after metal-induced crystallization of channelmaterial 20. Such may be a basis of thermodynamic drive of metal fromchannel material 20 into upper region 34 of gettering material 30.

The accumulation of metal within the upper region of gettering material30 may enable the metal to be effectively removed after it has servedthe purpose of inducing crystallization within channel material 20. FIG.10 shows construction 10 after the gettering material 30, and allmaterials overlying material 30, have been stripped from over the uppersurface 19.

The processing of FIGS. 2-10 may enable metal to be utilized formetal-induced crystallization of semiconductor channel material to forma crystallographic texture within the semiconductor material havinggrain boundaries 45 parallel to surfaces adjacent the channel material(for instance, the surfaces 25 and 27 of dielectric material 22).Further, the processing may enable all, or at least substantially all,of the metal to be removed from the channel material after serving thepurpose of inducing crystallization. In some embodiments theconstruction of FIG. 10 may be considered to comprise circuit components(for instance, memory cells, select gates, etc.) which utilize thesemiconductor channel material 20 in gated devices (with example gateddevices being memory cells comprising control gates 12, and select gatescomprising the gates 14 and 16). The quality of the gated devices may bequantitated in terms of Ion/Ioff characteristics of the devices. In someembodiments, metal removal from the semiconductor channel material willbe sufficiently effective that the Ion/Ioff characteristics of the gateddevices will be within a same order of magnitude as would occur if thesemiconductor channel material 20 had no metal therein (i.e., within afactor of ten); within a factor of five as would occur if thesemiconductor material had no metal therein, or even with a factor oftwo as would occur if the semiconductor material had no metal therein.For instance, in some applications Ion/Ioff characteristics of atransistor device (i.e., an example gated device) having pure siliconchannel material (i.e., having no metal within the channel material) maybe an Ion/Ioff ratio within a range of from about 10⁷ to about 10¹⁰.

The processing of FIGS. 2-10 may enable formation of constructionshaving semiconductor channel material that is entirely, or at least veryclose to entirely, metal-free (for instance, a metal concentration lessthan or equal to about 0.5 atomic percent); with such semiconductorchannel material having grain boundaries 45 aligned relative to adjacentsurfaces 25 and 27 of the gate dielectric 22.

The embodiment of FIGS. 3-10 has the gettering material 30 formed priorto providing the metal 42. In other embodiments, the metal may beutilized to induce crystallization within the semiconductor channelmaterial, and subsequently the gettering material may be provided. Anexample of such other embodiments is described with reference to FIGS.11-18.

Referring to FIG. 11, construction 10 is shown at a processing stagesubsequent to that of FIG. 2. The protective liner (i.e., metal-barriermaterial) 36 is formed across upper surface 19 to cover the second end26 of the semiconductor channel material 20 while leaving the first end24 of the semiconductor channel material exposed within opening 38. Theprotective liner 36 of FIG. 11 may comprise the same composition andthickness as discussed above for the protective liner 36 of FIG. 3.

A filter material 40 and metal 42 are provided over protective liner 36and extend into opening 38 so that the metal 42 is adjacent to the firstend 24 of the semiconductor channel material 20. The filter material maycomprise the compositions and thicknesses discussed above with referenceto the filter material 40 of FIG. 4, and the metal may comprise thecompositions and thicknesses discussed above relative to metal 42 ofFIG. 4. In some embodiments, metal 42 of FIG. 11 may comprise nickeland/or aluminum, and semiconductor channel material 20 may comprisesilicon.

Referring to FIG. 12, a short thermal process (for instance, a rapidthermal process having a duration of from about 10 minutes about 20minutes and a temperature within a range of from about 500° C. to about600° C.) is utilized to diffuse metal 42 into semiconductor channelmaterial 20 adjacent the first end 24, as is diagrammaticallyillustrated with arrows 43. The metal within semiconductor channelmaterial 20 is diagrammatically illustrated with stippling.

Referring to FIG. 13, the protective liner 36, filter material 40 andmetal 42 are removed from over surface 19. The metal which had diffusedinto a shallow region of semiconductor channel material 20 adjacent thefirst end 24 remains, as is diagrammatically illustrated with stippling.

Referring to FIG. 14, thermal conditions are utilized to induce generatemetal-induced crystallization (and/or metal-induced lateralcrystallization) within the semiconductor material 20 as isdiagrammatically illustrated utilizing arrows 43 to indicate migrationof the metal, and dashed-lines 45 to indicate formation of grainboundaries parallel to the parallel surfaces 25 and 27 of the gatedielectric material 22. The metal-induced crystallization ofsemiconductor material 20 transitions the material 20 from a firsttexture to a second texture, analogously to the transition discussedabove with reference to FIGS. 5-7.

Any suitable thermal processing may be utilized for the metal-inducedcrystallization. In some embodiments, the thermal processing maycomprise a temperature within a range of from about 370° C. to about550° C., for at least about 10 hours. In some embodiments, one or morecleaning steps (for instance, wet cleans) may be utilized to removemetal which may be on surface 19 adjacent one or both of the ends 24 and26 after the metal-induced crystallization.

Referring to FIG. 15, the gettering material 30 is formed over thesurface 19, and specifically across the first and second ends 24 and 26of the U-shaped channel material 20. The illustrated gettering material30 includes the first and second regions 32 and 34 discussed above withreference to FIG. 3; and may comprise any of the configurationsdescribed with reference to FIG. 3, such as, for example, separatediscrete layers and/or a gradient.

Referring to FIGS. 16 and 17, the metal migrates from the semiconductormaterial into the gettering material 30 and accumulates in the topregion 34 of the gettering material. The metal migration isdiagrammatically illustrated with arrows 43 in FIG. 16, and the metalaccumulation within the top region 34 is diagrammatically illustrated inFIG. 17 by stippling. In the illustrated embodiment the metalaccumulates above both of the ends 24 and 26 of the semiconductorchannel material. In other embodiments, the metal may accumulateprimarily over the end 26.

The metal migrates into the gettering material 30 due to such beingthermodynamically favored. As discussed above, the regions 32 and 34 ofthe gettering material are tailored so that thermodynamic forces causethe metal to be drawn into the lower region 32, and then to betransferred from the lower region 32 into the upper region 34. In someembodiments, both of regions 32 and 34 may be amorphous as deposited,and region 32 may have a higher amorphous-to-crystal transitiontemperature as compared to channel material 20 and region 34. Region 34may be at least partially crystallized through metal-inducedcrystallization while region 32 remains amorphous, and aftermetal-induced crystallization of channel material 20. Such may be abasis of thermodynamic drive of metal from channel material 20 intoupper region 34 of gettering material 30.

Referring to FIG. 18, the gettering material 30 (FIG. 17) is strippedfrom over the upper surface 19. The construction of FIG. 18 may beidentical to that described above with reference to FIG. 10.

The processing of FIGS. 15-18 (i.e., forming gettering material, thermalprocessing to drive metal from the semiconductor channel material intothe gettering material, removing the gettering material) may be repeatedmore than once if such is useful in reducing a metal concentration inthe semiconductor channel material to below a desired threshold (forinstance, less than or equal to about 0.5 atomic percent).

The embodiments of FIGS. 2-18 illustrate metal-induced crystallizationwithin U-shaped semiconductor channel regions. An advantage of theU-shaped channel regions is that they have two ends which are readilyaccessible. Methodology described herein may be extended to otherconstructions in which semiconductor material has two ends which arereadily accessible. For instance, FIG. 19 shows a construction 10 acomprising a plurality of tiers 70-73 stacked one atop the other. Eachtier has semiconductor channel material 20 extending from a first end 74to a second end 76 (with the ends 74 and 76 corresponding to sides ofconstruction 10 a). The tiers are spaced from one another to indicatethat there may be other materials or structures between the tiers. Insome embodiments, the device layers of FIG. 19 may be flipped upsidedown relative to the shown configuration during device fabrication.

Each tier comprises a plurality of transistor gates 80, and comprisesgate dielectric material 22 between the gates and the channel material20. Additionally, each tier comprises insulative material 82 on anopposing side of the channel material from the gate dielectric 22.

The gate dielectric 22 has a surface 90, and the insulative material 82has a surface 92; with the surfaces 90 and 92 being parallel to oneanother. The channel material 20 is between the parallel surfaces 90 and92.

In some embodiments the gates 80, gate dielectric 22 and channelmaterial 20 together form a plurality of thin-film-transistors. Theconstruction 10 a may thus correspond to thin-film-transistor NAND flashmemory (i.e., TFT-NAND flash memory).

Referring to FIG. 20, gettering material 30 is formed along the side 74of construction 10 a, and the filter material 40 and metal 42 are formedalong the opposing side 76 of the construction.

Referring to FIG. 21, thermal processing is utilized to cause metal 42to migrate along the tiers 71-73 from end 76 to end 74 and therebyinduce crystallization within the semiconductor channel material 20.Such crystallization forms grain boundaries within the semiconductorchannel material parallel to the surfaces 90 and 92, as isdiagrammatically illustrated with dashed lines 45.

Referring to FIG. 22, the gettering material 30, filter material 40 andmetal 42 are removed to leave a TFT-NAND flash memory configurationhaving semiconductor channel material 20 with grain boundaries parallelto the parallel surfaces 90 and 92 of the gate dielectric 22 andinsulative material 82.

The TFT-NAND flash memory comprises a plurality of memory cells 100(only a couple of which are labeled). The processing of FIGS. 19-22 maybe performed analogously to that described above relative to theembodiments of FIGS. 2-18 such that the desired crystallographicorientation within semiconductor channel material 20 is achieved, andsubsequently metal is entirely (or at least substantially entirely)removed from the semiconductor channel material so that the memory cells100 have desired electrical characteristics. In some embodiments themetal concentration within the channel material 20 at the processingstage of FIG. 22 will be low or non-existent (for instance, less than orequal to about 0.5 atomic percent) throughout an entirety of the channelregions so that all of the memory cells of the NAND flash memory haveIon/Ioff characteristics within a same order of magnitude as would occurif the semiconductor channel material 20 had no metal therein; within afactor of five as would occur if the semiconductor material had no metaltherein, or even with a factor of two as would occur if thesemiconductor material had no metal therein.

In some embodiments a first portion of a TFT-NAND flash memory stack maybe treated with the processing of FIGS. 19-22 prior to forming one ormore additional portions over said first portion. Each of the additionalportions may be subsequently treated with the processing of FIGS. 19-22.In some embodiments, TFT-NAND flash memory may be built one layer at atime, with individual layers being treated with the processing of FIGS.19-22 prior to forming the next layer thereover.

The structures and configurations discussed above may be incorporatedinto electronic systems. Such electronic systems may be used in, forexample, memory modules, device drivers, power modules, communicationmodems, processor modules, and application-specific modules, and mayinclude multilayer, multichip modules. The electronic systems may be anyof a broad range of systems, such as, for example, cameras, wirelessdevices, displays, chip sets, set top boxes, games, lighting, vehicles,clocks, televisions, cell phones, personal computers, automobiles,industrial control systems, aircraft, etc.

Unless specified otherwise, the various materials, substances,compositions, etc. described herein may be formed with any suitablemethodologies, either now known or yet to be developed, including, forexample, atomic layer deposition (ALD), chemical vapor deposition (CVD),physical vapor deposition (PVD), etc.

Both of the terms “dielectric” and “electrically insulative” may beutilized to describe materials having insulative electrical properties.The terms are considered synonymous in this disclosure. The utilizationof the term “dielectric” in some instances, and the term “electricallyinsulative” in other instances, may be to provide language variationwithin this disclosure to simplify antecedent basis within the claimsthat follow, and is not utilized to indicate any significant chemical orelectrical differences.

The particular orientation of the various embodiments in the drawings isfor illustrative purposes only, and the embodiments may be rotatedrelative to the shown orientations in some applications. The descriptionprovided herein, and the claims that follow, pertain to any structuresthat have the described relationships between various features,regardless of whether the structures are in the particular orientationof the drawings, or are rotated relative to such orientation.

The cross-sectional views of the accompanying illustrations only showfeatures within the planes of the cross-sections, and do not showmaterials behind the planes of the cross-sections in order to simplifythe drawings.

When a structure is referred to above as being “on” or “against” anotherstructure, it can be directly on the other structure or interveningstructures may also be present. In contrast, when a structure isreferred to as being “directly on” or “directly against” anotherstructure, there are no intervening structures present. When a structureis referred to as being “connected” or “coupled” to another structure,it can be directly connected or coupled to the other structure, orintervening structures may be present. In contrast, when a structure isreferred to as being “directly connected” or “directly coupled” toanother structure, there are no intervening structures present.

Some embodiments include an integrated structure having semiconductormaterial within a region between two parallel surfaces. Thesemiconductor material has grain boundaries parallel to the parallelsurfaces. At least one circuit component utilizes a region of thesemiconductor material in a gated device. The semiconductor material haslittle if any metal therein (for instance, less than or equal to about0.5 atomic percent metal) so that the gated device has Ion/Ioffcharacteristics within a same order of magnitude as would occur if thesemiconductor material had no metal therein.

Some embodiments include a method of forming an integrated structure. Aconfiguration is provided which has semiconductor material between apair of parallel surfaces. The semiconductor material has a firstcrystallographic texture. The parallel surfaces and semiconductormaterial extend between a first end and a second end. Metal is formedadjacent the first end. The metal comprises one or more metals selectedfrom the group consisting of aluminum, near-noble metal and noble metal.A first region of gettering material is formed adjacent the second end,and a second region of gettering material is formed across the firstregion of gettering material. The semiconductor material and first andsecond regions of gettering material are thermally processed. The metalinduces crystallization of the semiconductor material to transition thefirst crystallographic texture to a second crystallographic texture. Thesecond crystallographic texture has grain boundaries parallel to theparallel surfaces. Thermodynamics drives the metal along thesemiconductor material from the first end to the second end, then fromthe semiconductor material into the first gettering region, and thenfrom the first gettering region to the second gettering region. Thefirst and second gettering regions are subsequently removed.

Some embodiments include a method of forming an integrated structure. Aconfiguration is provided which has semiconductor material between apair of parallel surfaces. The configuration is a U-shaped NAND stringwith the parallel surfaces being U-shaped and on opposing sides of achannel region. The semiconductor material has a first crystallographictexture. The parallel surfaces and semiconductor material extend betweena first end along one side of the U-shape and a second end along anotherside of the U-shape, Metal is formed adjacent the first end. The metalcomprises one or more metals selected from the group consisting ofaluminum, near-noble metal and noble metal. The semiconductor materialis thermally processed with the metal therein. The metal inducescrystallization of the semiconductor material to transition the firstcrystallographic texture to a second crystallographic texture. A firstregion of gettering material is formed across the first and second ends,and a second region of the gettering material is formed across the firstregion of the gettering material. The semiconductor material and firstand second gettering regions of gettering material are thermallyprocessed, and thermodynamics drives the metal from the semiconductormaterial into the first gettering region, and then from the firstgettering region to the second gettering region. The first and secondgettering regions are subsequently removed.

Some embodiments include a method of forming an integrated structure. Aconfiguration is provided which has semiconductor material between apair of parallel surfaces. The configuration is a U-shaped NAND stringwith the parallel surfaces being U-shaped and on opposing sides of achannel region. The semiconductor material has a first crystallographictexture. The parallel surfaces and semiconductor material extend betweena first end along one side of the U-shape and a second end along anotherside of the U-shape. A first region of gettering material formed acrossthe second end, and a second region of gettering material is formedacross the first region of gettering material. The first and secondregions of the gettering material are patterned to cover the second endwhile leaving the first end exposed. Metal-barrier material is formedover the second region of the gettering material. The metal-barriermaterial is patterned to cover the second region of the getteringmaterial while leaving the first end exposed. Metal is formed over themetal-barrier material and adjacent the exposed first end. The metalcomprises one or more metals selected from the group consisting ofaluminum, near-noble metal and noble metal. The semiconductor materialand first and second regions of gettering material are thermallyprocessed. Thermodynamics drives the metal along the semiconductormaterial from the first end to the second end, then from thesemiconductor material into the first gettering region, and then fromthe first gettering region to the second gettering region. The first andsecond gettering regions are subsequently removed.

In compliance with the statute, the subject matter disclosed herein hasbeen described in language more or less specific as to structural andmethodical features. It is to be understood, however, that the claimsare not limited to the specific features shown and described, since themeans herein disclosed comprise example embodiments. The claims are thusto be afforded full scope as literally worded, and to be appropriatelyinterpreted in accordance with the doctrine of equivalents.

We claim:
 1. A method of forming an integrated structure, comprising: providing a configuration having semiconductor material between a pair of parallel surfaces, the configuration being a U-shaped NAND string with the parallel surfaces being U-shaped and on opposing sides of a channel region; the semiconductor material having a first crystallographic texture; the parallel surfaces and semiconductor material extending between a first end along one side of the U-shape and a second end along another side of the U-shape; forming metal adjacent the first end, the metal comprising one or more metals selected from the group consisting of aluminum, near-noble metal and noble metal; thermal processing the semiconductor material with the metal therein, the metal inducing crystallization of the semiconductor material to transition the first crystallographic texture to a second crystallographic texture; forming a first region of gettering material across the first and second ends, and forming a second region of the gettering material across the first region of the gettering material; thermal processing the semiconductor material and the first and second regions of the gettering material; thermodynamics driving the metal from the semiconductor material into the first gettering region, and then from the first gettering region to the second gettering region; and removing the first and second gettering regions.
 2. The method of claim 1 wherein the metal comprises aluminum.
 3. The method of claim 1 wherein the metal comprises near-noble metal.
 4. The method of claim 1 wherein the metal comprises noble metal.
 5. The method of claim 1 wherein the first and second regions of gettering material are comprised by two or more distinct layers.
 6. The method of claim 1 wherein the first region of the gettering material has a higher amorphous-to-crystal transition temperature than the semiconductor channel material and the second region of the gettering material.
 7. The method of claim 6 wherein the gettering material comprises at least one additional region between the first and second regions; and wherein said at least one additional region has a lower amorphous-to-crystal transition temperature than the first region of the gettering material and a higher amorphous-to-crystal transition temperature than the second region of the gettering material.
 8. The method of claim 1 wherein the first and second regions of gettering material are comprised by a structure having a first stoichiometry in the first gettering region, a second stoichiometry in the second gettering region, and a gradient from the first gettering region to the second gettering region; the first stoichiometry transitioning to the second stoichiometry along said gradient. 